Seam sealer apparatus and method of sealing seams on an asphalt road

ABSTRACT

Seam sealer for sealing seams in an asphalt paving operation has electric heaters and heats a seam area that includes a narrow strip of previously laid-down asphalt and a narrow strip of the road surface to be paved. A temperature sensor senses temperature of the seam area. A control system adjusts energy level supplied to the heaters, to obtain a pre-determined temperature on the road surface. The pre-determined temperature is close to the temperature of the fresh hot asphalt to be applied. An asphalt paver travels behind the seam sealer and applies fresh hot asphalt to the road surface still to be paved, overlapping it onto the previously laid down asphalt in the seam area. The fresh hot asphalt and the previously laid down asphalt form a molten mass, which is subsequently pressed to a smooth, fused and finished road surface by a road roller.

BACKGROUND INFORMATION

1. Field of the Invention

The invention relates to road paving equipment. More particularly, theinvention relates to a method of sealing pavement seams in asphaltpaving material and equipment for practicing the same method.

2. Description of the Prior Art

Applying asphalt pavement to roads frequently requires that the asphaltbe applied in sections, because the road is too wide to process in asingle pass. Thus, first one section of the road width is paved and thenthe second section. For reasons of simplicity, width sections will bereferred to hereinafter as “lanes,” although it is understood that theactual width of the paving step does not have to correspond to a drivinglane on the road. The area where one lane of asphalt overlaps anotherwill be referred to as the “seam area.”

Typically, a first lane will be paved along a long stretch of road andthe second lane paved at a later time, such as the next day or severaldays or even weeks later. No matter what the time difference is betweenpaving the first lane and the second lane, the asphalt laid down on thefirst lane will already have cooled to what shall be referred to as“road temperature” by the time fresh hot asphalt is applied to thesecond lane. “Road temperature” is the temperature of the road surface,and “road surface” may include a portion of the first lane and secondlane.

Asphalt is laid down warm, typically around 250 degrees F., so that itbonds with the substrate. Asphalt as it is being applied to the roadsurface shall be referred to hereinafter as “fresh hot asphalt,” todistinguish it from asphalt that has previously been laid down and hascooled to road temperature. After the first lane has been paved, freshhot asphalt is applied to the second lane such that it overlaps a fewinches with the asphalt of the first lane in the seam area. Ideally, thefresh hot asphalt overlapping the seam area should bond sufficientlywith the asphalt of the first lane, to form a water-impervious seam. Acommon and well known problem, however, is that, when fresh hot asphaltis laid down on top of asphalt that is at road temperature, thedifference in temperature prevents a good bond from forming. As aresult, cracks form along the seam. Water then seeps through the cracksunder the asphalt and down toward the sides of the roadway. Eventually,cracks form in the surface, which results further progressivedeterioration of the asphalt surface.

Efforts have been made to correct this fault. Some systems have used gastorch heaters arranged so that they move ahead of the paving machineryand heat the bonding edge of the previously laid-down asphalt. Oneproblem with gas heaters is that it is often difficult to control theheater to prevent too much heat from being applied and from beingapplied too directly. As a result, overheating is a common problem and,if overheated to the flash point, the asphalt can burst into flame.

What is needed, therefore, is a method of and system for heating a roadsurface for bonding with a fresh hot layer of asphalt. What is furtherneeded is such a system for controlling the heat that is applied to theroad surface.

BRIEF SUMMARY OF THE INVENTION

The invention is a seam sealer for asphalt paving and a method ofsealing an asphalt-paving seam. The seam sealer comprises a an electricheater for pre-heating the road surface to be paved, plus a power supplyunit for supplying energy to the heater, and a control system with aheat sensor. The heater may be one or more electric heaters. Certainadvantages are provided by using multiple heaters and the descriptionhereinafter will be based on the use of multiple heaters, although it isunderstood that it may be desirable to use a single heater in certainapplications. The heaters are mounted in a moving vehicle and arearranged such that they sequentially travel above the road surface inthe seam area and apply heat to the road surface. The seam area is anarrow strip of road surface that spans a few inches of the adjacentedges of the first and second lanes, i.e., a few inches the lanepreviously asphalted and a few inches of the lane still to be asphalted.The purpose of the heaters is to heat the road surface in the seam areato a desired temperature that is close to that of the fresh hot asphaltthat will be applied. The sensor monitors the temperature of the roadsurface and adjusts the heater output to maintain the desiredtemperature on the road surface. The desired temperature may be selectedto be some degrees above the temperature of the fresh hot asphalt thatis to be applied, so that temperatures of the fresh hot asphalt and thepreviously laid down asphalt on the road surface are close enough toallow the fresh hot asphalt and the previously laid down asphalt to forma molten mass that fuses together seamlessly when the road roller rollsover it and presses it together.

The heaters are extendable out from the vehicle, so that they arepositioned above the seam area. The heaters may be positioned at varyingdistances above the seam area. For example, a first heater may bepositioned 16 inches above the pavement, a second heater 12 inches, andso on. In this way, the series of heaters applies a graduated heat tothe seam area, initially pre-heating it with a low degree of heat, andthen applying a progressively higher degree of heat with each subsequentheater. In this way, the road surface in the seam area is heated to thedesired temperature in a very controlled manner, thereby eliminating therisk that the previously laid down asphalt in the first lane willcombust or chemically break down. Although the progressive applicationof heat is achieved by setting the heaters to progressively lowerdistances from the road surface, this may also be achieved by usingheaters of increasingly greater output capacities.

The seam sealer is moved alongside the seam area a pre-determineddistance in front of the paving equipment that is applying the fresh hotasphalt, so that an estimated amount of time lapses before the fresh hotasphalt is applied to the second lane. This allows the pre-heatedasphalt of the first lane to “cure” or normalize, before the fresh hotasphalt is applied. This curing process allows the heat from the seamsealer to penetrate a certain distance down into the previously laidasphalt of the first lane, so that the asphalt is well heated and notjust heated superficially. This heat penetration prior to applying thefresh hot asphalt ensures a better bond, because material from both thepreviously laid down asphalt and the fresh hot asphalt forms a moltenmass and, when pressed together, forms a water-tight, smooth, andseamless bond.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is described with reference to the accompanyingdrawings. In the drawings, like reference numbers indicate identical orfunctionally similar elements.

FIG. 1 is perspective schematic view of the seam sealer according to theinvention, shown moving alongside the seam area of a road ahead of anasphalt paver.

FIG. 2 is a side elevational view of the seam sealer of FIG. 1.

FIG. 3 is a top plane view of the seam sealer.

FIG. 4 is a front elevational view of the seam sealer according to theinvention, showing the heaters positioned over the seam area and thepaver following behind.

FIG. 5 is a block diagram of the electrical systems.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be described more fully in detail withreference to the accompanying drawings, in which the preferredembodiments of the invention are shown. This invention should not,however, be construed as limited to the embodiments set forth herein;rather, they are provided so that this disclosure will be complete andwill fully convey the scope of the invention to those skilled in theart.

FIGS. 1, 2, 3 and 4 illustrate conceptually a seam sealer 1000 accordingto the invention. The seam sealer 1000 is moving alongside a seam area Sin a roadway, in front of an asphalt paver 2000 that is laying downfresh hot asphalt. The seam sealer 1000 is shown being moved along theroadway by means of a tow vehicle V. Both the paver 2000 and the towvehicle V are conventional equipment and, as such, are not includedwithin the scope of the invention. The seam sealer 1000 may beconstructed as a towable platform or trailer that is towed by a towvehicle V or be incorporated into the moving vehicle itself. As shown inthe FIG. 1, a first lane L1 of asphalt has been previously laid down.The asphalt in this first lane L1 is at road temperature, as is the roadsurface of a second lane L2 that is yet to be paved. The surface of thesecond lane L2 is not limited to a specific type of surface. It can beold pavement that is being covered with a new layer of asphalt or agravel substrate. The seam sealer 1000 and the asphalt paver 2000 aremoving along the second lane L2. A seam area S is shown comprising anarrow strip along each side of a solid line that extends between L1 andL2. In other words, the seam area S includes a strip of previously laiddown asphalt in the first lane and a strip of still to be paved roadsurface in the second lane. The temperature of the road surface and thepreviously laid down asphalt in the seam area S is at “roadtemperature,” i.e., it may ambient temperature or be slightly warmer orcooler than the ambient temperature, depending on the season and theweather. FIG. 4 is a front elevational view that shows the seam sealer1000 with the heaters 200 positioned over the seam area S, including anoverlap dimension D, with the asphalt paver 2000 following some distancebehind it.

The seam sealer 1000 comprises an electrical heater 200, a sensor 400, acontrol system 500 for controlling the heaters 200, and a power supply600 for powering the heater 200 and other devices. The heater 200 willgenerally include two or more heaters, because this allows heat to beapplied progressively to the road surface, although it is understood,that the number and/or the capacity of the heaters in the series ofheaters 200 may vary according to a particular application. For purposesof illustration, the heater 200 as described herein shall be a series offour heaters 201, 203, 205, 207, each of which may include multipleindividual heaters. For example, if the capacity of the heater is toosmall for the desired heat output, two or more heaters may be providedwithin each heater, so as to create sets of heaters. In this way, theheaters 200 may now include, for example, four pairs of heaters 201-208,as shown in these FIGS. It is also possible that the first two heaters201 and 203 may each comprise a single heater and the last two heaters205 and 207 may each comprise a double heater 205/206 and 207/208.

The heaters 200 may be positioned at varying distances to the groundsurface. For example, the first heater 201 or 201/202 is a first heightH1, the second heater 203 or 203/204 a second height H2, the thirdheater 205 or 205/206 a third height H3, and the fourth heater 207 or207/208 a fourth height H4 from the surface of the seam area S. Theheaters 200 are preferably infrared heaters and preferably mounted onarms 220 that are hydraulically adjustable. Infrared frequency changesas the distance between heater and surface changes and providing theheaters 200 at varying heights “seasons” or cures the heat into thepavement at different infrared frequencies. Examples of suitable heightsH1-H4 are sixteen inches, twelve inches, eight inches, and four inches.The heaters 200 have a heating head that provides a heat-radiatingsurface area that is great enough to provide radiation over the seamarea S. The seam area S is shown in FIG. 1 as the area between twodashed lines and the solid line that indicates the edge of the asphaltlayer in the first lane L1. FIG. 3 shows the heating heads of theheaters 200 extending into the first lane L1 for a distance thatcorresponds to the overlap dimension D. An example of a suitable overlapdimension is nine inches. Thus, the road surface in the seam area S,i.e., a narrow strip of the sub-surface in the second lane 2 and anarrow strip of the previously laid down first lane L1, are heated tothe same temperature, this temperature being close to the temperature ofthe fresh hot asphalt that is to be applied to the second lane L2.

Other types of electric heaters may be used and the heaters do notnecessarily have to be positioned at varying distances to the groundsurface. Doing so provides certain advantages, discussed above, but itis also possible to provide a series of electric heaters that arepositioned at the same height relative to the ground surface. It is alsopossible to provide a series of heaters, all set at the same heightabove the road surface, but that vary in the heat output, so as toemulate the effect of the infrared heaters that are positioned atvarying heights. The inventor has determined that it is most efficientto provide progressively greater heat to the road surface, in order toheat it to the desired high temperature, yet avoid the danger of theasphalt combusting or from breaking down. A particular advantage ofelectric heaters is that the heat is radiated in a straight path throughair and, thus, in contrast to gas heaters, windy conditions will notsignificantly diminish the amount of heat that is radiated onto thepavement. Providing heat over a period of time from the series ofheaters 200 also ensures that the heat penetrates to a depth that isnecessary to obtain a good bond with the fresh hot asphalt that is beinglaid down.

The control system 500 and temperature sensor 400 control the amount ofenergy that is supplied to the heater 200 by the power supply 600. Thetemperature sensor 400 is mounted such, that it extends into the overlapdimension D close to the asphalt surface or generally into the seam areaS. The temperature sensor 400 measures the surface temperature and sendscorresponding signals to the control system 500. If the measuredtemperature varies from the set point for the pre-determined or desiredtemperature, the control system 500 adjusts the power to be sent fromthe power supply 600 to the heaters 200 accordingly. Various types ofsensors may be suitable for this application, but one particularlysuitable sensor is a laser temperature probe. The combination ofcontrolling the amount of power supplied to the heaters and controllingor adjusting the distance of the heating heads from the surface of thepavement to be heated enables a close control of the road surfacetemperature.

In conventional paving systems, the previously laid down asphalt in thefirst lane L1 is heated by a road roller during the rolling process,that is, after the asphalt for the second lane L2 has been applied.Heating the road surface ahead of the paver 2000 with the seam sealer1000 has the advantage of allowing the heat to be applied such, that itpenetrates farther into the pavement and, ideally, completely throughthe layer of the previously laid down asphalt in the first lane L1 andthrough the top layer of substrate in the second lane L2. Although thisis by no way intended to be limiting, use of the seam sealer 1000 in apaving operation will be somewhat as follows: The paver 2000 travels at50 ft/min and, ideally, somewhere between 50 and 75 feet behind the seamsealer 1000. Following the paver is a conventional road roller R thatrolls over the seam area S and presses the seam to a smooth finishedsurface. Prior to applying the fresh hot asphalt in the second lane L2,the road surface in the seam area S, which includes previously laid downasphalt in the first lane L1 and the existing road surface or substratein the second lane L2, will initially be at road temperature. The seamsealer 1000 heats the road surface in the seam area S to apre-determined temperature that is selected such that the temperature ofthe road surface will be hot enough to allow the fresh hot asphalt fromthe paver 2000 and the previously laid down asphalt in the first lane L1to form a molten mass, which is then pressed into a smooth, finished andseamless surface by the road roller R. The pre-determined temperature isadjusted according to the parameters of the specific paving operation.For example, on cool windy days, the seam area S may be heated a greaternumber degrees above the temperature of the fresh hot asphalt in thepaver 2000, to ensure that the road surface in the seam area S is at theproper temperature when the fresh hot asphalt is applied. On hotwindless days, the seam area S may be heated to just the temperature ofthe fresh hot asphalt, or even to a temperature that is a few degreeslower, if it is known that the temperature of the heated road surfacewill still be hot enough when the fresh hot asphalt is applied to it toallow the fresh hot asphalt and pre-heated previously laid down asphaltto form the desired molten mass.

The power supply 600 is preferably a diesel generator, which generatesthe electrical power for the heaters 200, a lighting system, if one isprovided, the sensor 400 and the control system 500. Additional sensors700 may also be provided. For example, the Department of Transportation(DOT) has specific guidelines on the temperature of the asphalt that isapplied. A GPS receiver 701 may be integrated into the sensor 400 andcontrol system 500, so as to allow data that correlates temperature andGPS data points to be gathered and stored for future analysis.Similarly, a motion sensor 702 may also be incorporated into the sensor400 and linked to the control system 500, to control the energy outputof the heaters 200 as a function of the speed of travel. For example, acertain energy output is required when moving at 50 feet/hour, thedesired speed of the paving operation. When the speed of the seam sealer1000 slows down or stops, because of some obstruction down the line, theenergy output of the heaters 200 may be reduced, to prevent the asphaltfrom overheating, yet keep the heaters warm enough to very quickly getup to the desired heating level, as soon as the seam sealer 1000 is inmotion again.

The following information is provided for enablement purposes only.Information as to size and type of heater and size and type of generatoris not intended to be a limitation on the scope of the invention. Anembodiment of the seam sealer 1000 according to the invention is as afour-wheeled trailer pulled by a tractor with a three-point hitch. Thetrailer may be pulled from each end. To this end, the temperature sensor400 is mountable on each end of the trailer, so that the trailer may betowed in both directions. The tractor provides the hydraulic power tooperate the hydraulic controls for the controlled heaters 200. A seriesof heaters are spaced along one side of the trailer. In the embodimentshown, four paired sets of infrared heaters 201-208 were used, each setof heaters being positioned a progressively shorter distance from theroad surface. For example, the sets of heaters 201/202, 203/204/205/206,and 207/208 are set to sixteen, twelve, eight, and four inches,respectively, above the surface of the overlap area. It is understoodthat the series of heaters may include any number of heaters and thatthe heaters do not have to be paired sets. The size of each heater201-208 is 5400 Watts. The heating heads of the heaters 201-208 have aheat-radiating surface area that will heat a sufficiently wide seam areaA and, in the embodiment shown, is 18×12 inches, so that the overlaponto each lane L1 and L2 is nine inches. An example of a suitableinfrared heater is a medium wavelength V-Series heater from SolarProducts, Inc. of Pompton Lakes, N.J. The generator has a 10 kW outputcapacity. An example of a suitable generator is a Kohler EmergencyStandby Diesel Generator Set, Model 10REODB from Kohler Generators ofWakefield, Mass. The hydraulic power for operating the hydraulicallydriven arms for the heaters 200 is a conventional system that istypically available on tractors. Hydraulic systems are well known andthe specifics of the hydraulic arms for positioning the heaters 200 arenot included within the scope of the invention and are not describedherein in detail. The heaters 201-208 are adjusted up and down to bestfit the particular paving application. Once the height is adjusted, theamperage is adjusted to achieve the desired exit temperature. Thepre-heated, previously laid down asphalt in the first lane L1 has timeto normalize or cure, in other words, for the temperature penetrate intothe asphalt, asphalt will now bond together in a molten state, resultingin a water-tight, smooth, seamless bond when the road roller presses ittogether.

FIG. 5 is a block diagram, illustrating the various electricalcomponents of the seam sealer 1000. Examples of the electricalcomponents are as follows:

-   9 heater head relay 1 & 2-   10 heater head relay 3 & 4-   11 heater head relay 5 & 6-   12 heater head relay 7 & 8-   13 200 amp main circuit-   14-17 50 amp circuit breakers-   18-21 20 amp circuit breakers-   23 240 V power feed relay-   26 hydraulic pump-   27 reset machine relay-   28 master control relay-   29 spot light-   30 12 V LED lights-   31 battery from generator-   32 120 V ground fault resetable 4×receptacle-   33 USB communication port-   35 LED temperature display-   SW1 start generator enable switch-   SW2 enable 240 V feed from generator switch-   SW3 on/off heater heat switch-   SW4 on/off light switch-   SW5 reset machine switch-   SW6 emergency stop switch-   SW7 LED lights on/off switch-   SW8 on/off hydraulic pump switch-   FL1 fusible link

It is understood that the embodiments described herein are merelyillustrative of the present invention. Variations in the construction ofthe seam sealer may be contemplated by one skilled in the art withoutlimiting the intended scope of the invention herein disclosed and asdefined by the following claims.

1. Apparatus for sealing a seam on an asphalt roadway, said apparatuscomprising: a power generator; a series of electric heaters; atemperature sensor for sensing temperature on a road surface; and acontrol system for controlling heat output of said series of heaters;wherein said power generator supplies power to said series of electricheaters, said control system, and said temperature sensor; wherein saidcontrol system receives a temperature input from said temperaturesensor, compares said temperature input with a pre-determined value andadjusts said power supplied to said heaters by said power generator, soas to achieve and maintain a temperature that corresponds to saidpre-determined value.
 2. The apparatus of claim 1, wherein said heatersin said series of heaters are positioned at varying heights relative tosaid road surface.
 3. The apparatus of claim 2, wherein said series ofheaters includes at least two infrared heaters and wherein a firstinfrared heater is a first distance from said road surface and a secondinfrared heater is a second distance from said road surface.
 4. Theapparatus of claim 2, wherein at least one heater in said series ofheaters comprises a set of heaters that includes two or more individualheaters.
 5. The apparatus of claim 1, wherein said power generator is adiesel-fueled generator.
 6. The apparatus of claim 1, wherein saidtemperature sensor is a laser temperature sensor.
 7. The apparatus ofclaim 1, further comprising an additional sensor.
 8. The apparatus ofclaim 7, wherein said additional sensor is a GPS receiver.
 9. Theapparatus of claim 7, wherein said additional sensor is a motion sensor.10. (canceled)
 11. (canceled)
 12. (canceled)
 13. (canceled)
 14. A methodof sealing a seam in a roadway, comprising the steps of: heating apreviously laid section of roadway with a plurality of heating units;placing a new section of roadway in substantial proximity to thepreheated roadway; creating a molten mass between the preheated and newsection of roadways; and applying a force to the molten mass to create aseamless section of roadway.
 15. The method of claim 14, wherein eachheating unit comprises an infrared electric heater.
 16. The method ofclaim 15, further comprising the step of: applying a pre-determinedquantity of heat by said plurality of heating units, wherein eachsubsequent heating unit of said plurality applies a greater quantity ofheat than the previous heating unit.
 17. The method of claim 16, furthercomprising the step of: positioning each heating unit of said pluralitya pre-determined distance from the roadway, wherein each subsequentheating unit is positioned a smaller distance from the roadway than theprevious heating unit.
 18. The method of claim 17, wherein each heatingunit is disposed to be individually calibrated in relation to thedistance of each heating unit from the roadway.
 19. The method of claim18, further comprising the steps of: providing a power supply for eachheating unit; and providing a control system for monitoring the powersupply to each heating unit.
 20. The method of claim 19, furthercomprising the step of: selecting a temperature level in the controlsystem to provide for the power supply of each heating.
 21. The methodof claim 20, further comprising the step of: providing a temperaturesensor for sensing a temperature of the roadway.
 22. A method of sealinga seam in a roadway, comprising the steps of: heating a previously laidsection of roadway with a plurality of heating units within a singularheating cycle; placing a new section of roadway in substantial proximityto the preheated roadway, wherein a portion of the new section isdisposed to overlap with a portion of the previously laid section;creating a molten mass between the preheated and new section ofroadways; and applying a force to the molten mass to create a seamlesssection of roadway.
 23. The method of claim 22, wherein each heatingunit comprises an infrared electric heater.
 24. The method of claim 23,further comprising the step of: applying a pre-determined quantity ofheat by said plurality of heating units, wherein each subsequent heatingunit of said plurality applies a greater quantity of heat than theprevious heating unit.
 25. The method of claim 24, further comprisingthe step of: positioning each heating unit a pre-determined distancefrom the roadway, wherein each subsequent heating unit is positioned asmaller distance from the roadway than the previous heating unit. 26.The method of claim 25, wherein each heating unit is disposed to beindividually calibrated in relation to the distance of each heating unitfrom the roadway.
 27. The method of claim 26, further comprising thesteps of: providing a power supply for each heating unit; and providinga control system for monitoring the power supply to each heating unit.28. The method of claim 27, further comprising the step of: selecting atemperature level in the control system to provide for the power supplyof each heating.
 29. The method of claim 28, further comprising the stepof: providing a temperature sensor for sensing a temperature of theroadway.